The present invention relates to a device for pumping fluid with a hydraulic pump and a drive mechanism. The hydraulic pump is an external gear pump and is an independent component capable of being coupled to various types of drive mechanisms as additional components in the manner of a building block system. For this reason, it is in the form of a one-piece coupling piece. Various hydraulic tanks, especially ones with different tank capacities, are provided as a third type of component. A particular hydraulic tank on one side is connectible to the coupling piece. The particular drive mechanism on the other, opposite side is connectible to this coupling piece. For such purpose, the coupling piece on at least one side has a flange element. Sealing means are provided between coupling piece and drive mechanism as well as the hydraulic tank.
DE-A-195 14 749 describes a device for pumping fluid with a radial piston pump as hydraulic pump and a drive mechanism for driving the pump. The conventional device is likewise modular in structure in the manner of a building block system. The independent component forms a multipart element with the radial piston pump, and is built correspondingly large axially so that the conventional pump device is on the whole large and cannot be used in every installation case, especially under cramped installation conditions. In addition, because of the large number of individual piston pump elements required for the radial piston pump, susceptibility to breakdowns in operation is natural to a certain degree. In view of the great variety of parts, production and use of the radial piston pump as a hydraulic pump are also expensive.
Such pump devices, which are also called pump assemblies, are used among other things for hoisting and also lowering loads by hydraulic mechanisms, for example, in the area of cargo platforms in trucks, automobile platform lifts, mobile elevating platforms, or the like. In the mobile motor vehicle area, in which frequently only battery power is available, direct-current motors are used as drive mechanisms. In contrast, in the area of commercial firm installations or the like where direct current is available, the relevant pump device with a rotary current motor is employed.
In the relevant conventional solutions (e.g., DE-U-296 01 201), a special assembly solution is available for each special application, one which meets the special operating requirements. Since an independent technical concept is to be made available for each application, such solutions are expensive to apply in production. A large number of different structural shapes and structural components must be stocked as a function of customer requirements.
As a further development of the concept of configuring pumping devices or pump assemblies as a modular building block system, DE-A-32 27 926 proposes providing a hydraulic unit with a flange-like base plate on one side surface. On that one side, a hydraulic pump is removably fastened along with a housing tightly enclosing the pump and serving as container for the hydraulic medium. On the other side surface, an electric motor is mounted removably and opposite the pump. The motor drive shaft extends perpendicularly to the two side surfaces. In this conventional solution the hydraulic pump is a component of the hydraulic tank. This arrangement reduces the storage capacity. The flange-like base plate, in contrast, is provided with drill holes, perforations or the like forming all the connecting lines required for mounting of various hydraulic pumps, motors, valves, control elements, or the like. They end on one side or peripheral surface of the flange-like base plate, where fastening means for the components and for their connection are provided. The relevant conventional hydraulic unit as a pumping device is large in size and cannot be employed in every application if the space available for mounting is especially restricted.
DE-A-196 27 405 discloses a device for pumping fluid. The conventional pump layout includes a hydraulic tank with a filter and external gear pump connected by a drive shaft to an electric motor. The hydraulic tank and electric motor are mounted on opposite sides of the pump housing, which serves as coupling piece. The electric motor engages an annular recess in an end plate on an accompanying adjustable flange of this end plate. The hydraulic tank is held in place by a clamp on a flange-like seating surface. As viewed along a longitudinal section following the longitudinal axis of the pump layout, the pump housing is T-shaped in outline graduated through various widths. Replacement of the hydraulic tank on the side of the coupling piece with the drive mechanism is not possible, so that the possibility of adaptation to comply with stated customer wishes is restricted.
Objects of the present invention are to provide improved devices for pumping a fluid so that the manufacturing and overall costs are reduced and that a large number of customer wishes can be satisfied with a small number of components.
Other objects of the present invention are to provide a reliably operating pump unit, without the need for reducing the capacity of a tank container, which can be installed under extremely cramped installation conditions to conserve space and yet is just as efficient as a comparable conventional products.
The foregoing objects are basically attained with a hydraulic tank, a drive mechanism and a hydraulic pump housed in a coupling piece in the form of a base plate. On its side opposite the flange element, the coupling piece has another flange element adapted to the first flange element from the viewpoint of its external dimensions. Both flange elements have on their outer circumference a radial recess for engagement of a sealing means which may be overlapped by the free end of the hydraulic tank. The hydraulic tank and the drive mechanism can be connected while together on one side or on opposite sides of the coupling element. The pump device can be assembled as a compact unit for a large number of applications with the smallest possible number of components. In the process, the components already available may be combined at will with each other in accordance with customer instructions to form a marketable unit. Hence, the device of the present invention yields a building block system. Equivalent parts are used to produce a large variety of different embodiments at low cost. In this instance, the hydraulic tank may incorporate the drive mechanism and be mounted together with such drive mechanism on the side of the coupling piece provided for this purpose.
The hydraulic pump is incorporated and fully integrated into the base plate in the form of an external gear pump. The entire capacity of the tank unit to be connected is available. In addition, as a result of integration of the external gear pump, the length of the fluid lines and control lines is reduced. Such reduction facilitates reliability in operation with low pressure losses. Since the external gear pump has only two gears as actuating and drive elements, installation space is conserved and is cost effective. Such arrangement also promotes reliability of operation. In addition, the external gear pump is easier to design on the basis of its volume throughput for a wide variety of applications. It is easier to design the fuel pump on the basis of its geometric dimensions.
In addition, in the event of breakdown and for maintenance purposes, the hydraulic pump may be replaced simply by replacing the coupling piece. Because of the plate like configuration of the coupling piece, the hydraulic pump itself is easily accessible for purposes of repair and maintenance.
Other objects, advantages and salient features of the present invention will become apparent form the following detailed description, which, taken in conjunction with the annexed drawings, discloses preferred embodiments of the present invention.